Question ID: #290

NevinsNevins Posts: 29Member ■□□□□□□□□□
I ran into this question which I believe to be in error. Store-and-forward does do error checking in the form of a crc and it's not reducing latency by doing so. I would like to point out even the explanation states 2 of the 4 answers to question #290 are wrong.


Question ID: #290

Which of the following are characteristics of the store-and-forward switching method?
A. Reduces latency by skipping error checking. (wrong)
B. Forwards the frame as soon as it reads the destination address and determines the outgoing interface.
C. The entire frame is copied into the buffers of the switch, which computes a cyclic redundancy check before forwarding the frame.
D. Discards frames smaller than 64 bytes and frames larger than 1518 bytes.



Explanation:
The other two answers describe the cut-through switching method.
A frame smaller than 64 bytes or larger than 1518 bytes is called a runt.

Comments

  • bbarrickbbarrick Posts: 241Member
    A and B are characteristics of cut through switching not store and forward. The correct answers, to me, it would seem are C and D.
  • WebmasterWebmaster Posts: 10,292Admin
    Nevins wrote:
    I would like to point out even the explanation states 2 of the 4 answers to question #290 are wrong.

    Indeed. I wrote that question+explanation myself and it looks like answer A was incorrectly set to 'correct' in our test engine while it's clearly one of the two answers related to cut-through switching method. Fixed. Thanks, and nice catch! (considering how many thousands have taken these tests). I"ll check out your other post in a bit.
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